Trigger speed control switch

摘要

A speed control subassembly is made by providing a generally flat heat sink plate having a laterally-formed collector strip at its upper edge. A double-sided-adhesive insulator tape strip is stuck to the heat sink, this tape having a hole large enough to receive a thyristor chip so that the thyristor anode contacts the heat sink with solder paste therebetween. Two formed terminal strips extending in opposite directions are stuck to the tape so that one contacts the cathode and the other contacts the gate of the thyristor chip with solder paste therebetween. A chip capacitor is placed across the terminal strips with solder paste therebetween. A small force is applied to the capacitor and then heat is applied to the stack of parts to solder the parts together and to the heat sink and to set the adhesive resin. This subassembly is then placed into a trigger switch housing and connected to the contacts and variable resistor thereof to provide a trigger speed control switch for portable tools.